When medical procedures or operations require cannulation of a tubular or vascular structure or organ in the human body, guide wires are typically employed. Due to the flexibility, softness of the tip and narrow gauge of a typical guide wire, it is advantageous to first insert a guide wire into the organ to help position a larger diameter catheter or other instrument needed for the procedure. Some organs have characteristics which make the use of conventional straight guide wires difficult. For example, standard techniques using conventional guide wires for endoscopic cannulation of the cystic duct are not entirely satisfactory.
The cystic duct connects the gallbladder and the common bile duct. The cystic duct, however, has unique characteristics which distinguish it from other tubular organs. The mucous membrane lining the interior of the cystic duct has several crescentic folds commonly called valves of Heister, the exact function of which is still unclear. Typically, the number of folds ranges from five to twelve. The folds are directed and obliquely round having an appearance of a continuous spiral valve. The presence of these spiral folds, in combination with the tortuosity of the cystic duct, makes endoscopic cannulation of the cystic duct extremely difficult. The valves of Heister impede the introduction of surgical instruments and are prone to lacerations. There is a great need for a device which makes cannulation of the cystic duct both safe and easy for, among other things, the diagnosis and treatment of gallstone disease.
There has been extensive research and development committed to the design of a suitable guide wire for use in conjunction with a preshaped catheter system to allow the cystic duct and gallbladder to be reliably catheterized, retrograde, using an endoscope or other apparatus. Because of the unique structure of the cystic duct folds, successful catheterization of the cystic duct and the gallbladder during endoscopic retrograde procedures is obtainable only when favorable anatomical situations exist. Because of the difficulty in negotiating the cystic duct, it is only exceptional cases where selective catheterization can be achieved using conventional guide wires.
Frimberger et al., Endoscopy 15:359 (1983), was among the first to report attempts to routinely cannulate the gallbladder with the aid of a special endoscope. The system was extremely complicated, however, and did not facilitate reliable cannulation.
One of the most advanced guide wire and catheter systems for cannulation of the gallbladder and cystic duct was disclosed in Foerster et al., Endoscopy 20:30, 33 (1988). Foerster et al. discloses a specially made thin steerable guide wire with a straight, 6 cm long soft distal tip. In Foerster et al., the thin, straight steerable guide wire is inserted into a pre-shaped catheter pre-positioned near the opening of the cystic duct. The guide wire is then advanced through the catheter and into the cystic duct. Once positioned in the cystic duct, the thin, straight guide wire must be carefully manipulated to successfully traverse the valves of Heister. The use of a conventional straight guide wire, as taught in Foerster et al., may result in the guide wire catching on the cystic duct folds, impeding its forward progress and causing injury to the duct.
Hence, it is an object of this invention to provide a guide wire designed to be used in conjunction with a preshaped open hook configuration catheter system, as an example that described by Foerster et al., for endoscopic retrograde cannulation of the gallbladder. The unique configuration of the guide wire invention is the result of careful research into the anatomy of the cystic duct and the valves of Heister. The invention comprises guide wire having a unique construction which provides forward traction upon application of torsional force along the guide wire while at the same time employing an ultra-low friction surface which reduces friction between the guide wire and a catheter when used in conjunction.